If the integral 525 0 2 2x 112x (1+ 52x ) 12dx is equal to (n 2-64 ), then n is equal to .
Answer
176
Solution
I= 0 22 x 132x (1+ 52x ) 12dx
Put x=t2, x dx=-2t dt ⇒ I=4 01 t14 1+t5 dt
Put 1+t5=k2, 5t4dt=2k dk ⇒ I= 85 1 2 (k2-1 )2k2 dk
= 85 [ k77- 2k55+ k33 ]1 2
= 85 [ ( 8 27- 8 25+ 2 23 )- ( 17- 25+ 13 ) ]
= 85 22 2-8105
525I=8 (22 2-8 )=176 2-64 ⇒ n=176
Answer: 176